In the related art, a waterproof connector for connecting electric wires has been mounted on an automobile or the like. For example, a waterproof connector has been known which includes a female connector in which a tubular inner housing formed with a cavity for accommodating a female terminal and a tubular outer housing surrounding the inner housing are integrally formed, and a female connector having a tubular male housing in which a cavity for accommodating a male terminal is formed, and the a waterproof connector is formed by fitting both connectors.
In this type of waterproof connector, an annular rubber packing is mounted on the outer circumferential surface of the inner housing of the female connector. When both connectors are fitted together, the male housing is inserted into a gap between the inner housing and the outer housing of the female connector. The packing is brought into close contact with an outer circumferential surface of the inner housing and an inner circumferential surface of the male housing, respectively, thereby preventing water from entering the gap between the cavities.
However, this type of waterproof structure requires a space for mounting the packing inside the female connector. Therefore, the outer diameter size of the waterproof connector increases. Also, the male housing is inserted into the female housing, while pressing the packing. Therefore, the load upon insertion of the male housing is increased. Thus, as a waterproof structure which does not use packing, for example, a structure is known in which a disc-shaped elastic plate is provided on the inner surface on the back side of the female housing, and when both connectors are fitted together, the housing leading end in the fitting direction of the male housing inserted into the female housing is brought into contact with the sealing plate to prevent water from entering (for example, see Patent Literature 1).